Expression of Group I metabotropic glutamate receptors on phenotypically different cells within the nucleus of the solitary tract in the rat

J. R. Austgen, A. Y. Fong, C. M. Foley, P. J. Mueller, D. D. Kline, C. M. Heesch, E. M. Hasser*

*Corresponding author for this work

    Research output: Contribution to journalArticle

    21 Citations (Scopus)

    Abstract

    Group I metabotropic glutamate receptors (mGluRs) are G-coupled receptors that modulate synaptic activity. Previous studies have shown that Group I mGluRs are present in the nucleus of the solitary tract (NTS), in which many visceral afferents terminate. Microinjection of selective Group I mGluR agonists into the NTS results in a depressor response and decrease in sympathetic nerve activity. There is, however, little evidence detailing which phenotypes of neurons within the NTS express Group I mGluRs. In brainstem slices, we performed immunohistochemical localization of Group I mGluRs and either glutamic acid decarboxylase 67 kDa isoform (GAD67), neuronal nitric oxide synthase (nNOS) or tyrosine hydroxylase (TH). Fluoro-Gold (FG, 2%; 15 nl) was microinjected in the caudal ventrolateral medulla (CVLM) of the rat to retrogradely label NTS neurons that project to CVLM. Group I mGluRs were distributed throughout the rostral-caudal extent of the NTS and were found within most NTS subregions. The relative percentages of Group I mGluR expressing neurons colabeled with the different markers were FG (6.9±0.7) nNOS (5.6±0.9), TH (3.9±1.0), and GAD67 (3.1±1.4). The percentage of FG containing cells colabeled with Group I mGluR (13.6±2.0) was greater than the percent colabeled with GAD67 (3.1±0.5), nNOS (4.7±0.5), and TH (0.1±0.08). Cells triple labeled for FG, nNOS, and Group I mGluRs were identified in the NTS. Thus, these data provide an anatomical substrate by which Group I mGluRs could modulate activity of CVLM projecting neurons in the NTS.

    Original languageEnglish
    Pages (from-to)701-716
    Number of pages16
    JournalNeuroscience
    Volume159
    Issue number2
    DOIs
    Publication statusPublished - 17 Mar 2009

    Keywords

    • caudal ventrolateral medulla
    • Fluoro-Gold
    • GAD67
    • immunohistochemistry
    • nitric oxide
    • tyrosine hydroxylase

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